Pseudo-Bridges allow nodes on a first network to believe that nodes on a second, different network are actually disposed on the first network. Briefly, a device, such as a gateway, may have network interfaces on two different networks, which may be referred to as a first network and a second network.
Internet Standard STD 37 defines an address resolution protocol (ARP). The ARP protocol allows a device to learn the link layer address, in other words, the Media Access Control (MAC) address, of a second device based on the second device's Internet Protocol (IP) address. Typically, the device transmits a broadcast message, known as an ARP message, containing the IP address and requesting the MAC address associated with that IP address. Once a response is returned to the device, that device uses that MAC address whenever communicating with the second device.
There exists a concept known as Proxy ARP, in which one device responds to the ARP message on behalf of another device. For example, a plurality of devices may be disposed behind a firewall. In this case, the firewall would respond to any ARP requests for the devices disposed behind it, responding with its own MAC address.
Proxy ARP can also be used to bridge two networks such that the devices present on a first network appear to devices on the second network as being part of that second network. A gateway that connects two networks and utilizes this concept may be referred to as Pseudo-Bridge.
Pseudo-Bridges maintain a first list of devices that are in communication with its first network and a second list of devices that are in communication with its second network. In certain embodiments, the first and second networks may be different, such as one is an Ethernet network and the second is a Wi-Fi network. In other words, in certain embodiments, a Pseudo-Bridge is an OSI Layer 3 solution that allows wired and wireless networks to appear as a single network.
When a device on the first network transmits an ARP request to a second device, the Pseudo-Bridge determines if that second device is on the second network by checking the second list. If it is, the Pseudo-Bridge responds to the ARP request by transmitting the MAC address of the network controller disposed on the first network. If the second device is not located on the second network, the Pseudo-Bridge does not respond to the ARP request.
This approach is successful as long as the Pseudo-Bridge is able to successfully construct the first and second lists. However, certain situations may cause those lists to be inaccurate or incorrect. Traditional techniques for detecting loops, such as Spanning Tree protocol (STP), are not useful, as these are Layer 2 solutions. Therefore, it would be beneficial if there were a system and method for correctly configuring the Pseudo-Bridge in these instances.